[clang] [clang-tools-extra] [llvm] [clang] Simplify device kernel attributes (PR #137882)

[Nick Sarnie via cfe-commits]

sarnex wrote:

Any final comments on this @AaronBallman @erichkeane @arsenm @AlexVlx @yxsamliu, would appreciate a review, thanks!

https://github.com/llvm/llvm-project/pull/137882